基于级联-并联变换器的贯通式牵引变电所系统研究

摘要

为了解决既有电气化铁路存在的电分相、无功、负序与谐波问题,以及贯通式牵引变电所容量问题,提出一种基于级联-并联变换器的贯通式牵引变电所系统.牵引变电所采用二极管钳位型三电平NPC变换器作为基本结构,同时采用变换器级联和并联实现牵引变电所的容量提升,通过载波移相空间矢量脉宽调制SVPWM策略控制变换器输出电压.深入分析变电所内变换器并联产生环流的原因,设计了将双闭环控制与下垂控制策略结合的共享同步信号环流抑制策略,并首次应用于级联-并联变换器的牵引变电所系统,抑制系统内环流.通过仿真验证该结构的可行性,并通过小功率实验平台验证控制策略与调制策略的正确性.%To address the problems of electrification phase, reactive power, negative sequence and harmonic in electrified railway, and the capacity problem of traction power substation, an advanced cophase traction power substation system based on the cascade-parallel converter was proposed.The 3-level neutral point clamped (NPC) inverter was used as the basic structure in the traction power substation, while the converter was cascaded and paralleled to improve the capacity of the substation.The converter output voltage was controlled by phase shift carrier space vector pulse width modulation (SVPWM) modulation strategy.This paper analyzed the causes of circulating current in parallel converter in the substation, designed a shared synchronization signal control strategy, combined with dual closed-loop control and sagging control strategy.The control strategy was used in the substation system to suppress the circulation in the system.In the end, the feasibility of the structure was verified by the simulation, while the control strategy and modulation strategy were verified by experiment.